Carburetor



Oct. 13, 1959 H. H. DIETRICH ET AL CARBURETOR Filed Dec. 20. 1955 IN V EN T0125 H0 when H 0/15 TE/CH e luc/z/s WP/ITEESON (1kg K/ N T ATTORNEY masses Patented Oct. 13, 1959 CARBURETOR Howard HrDieh'ich and Lucius William Paterson, Rochester, N.Y., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application December 20, 1955, Serial No. 554,283 .10 Claims. (Cl. 192-.084)

This invention relates to carburetors for internal combustion engines used in automotive vehicles and is directed particularly to means for controlling the supply of idling mixture delivered to the intake passage under certain operating conditions, particularly during deceleration following a closing movement of the throttle.

In automative carburetors in which idling mixture is supplied to the'intake or mixture passage-between the throttle and the engine, when the throttle is moved toward closed position to effect deceleration and the engine is being driven by the vehicle, the idling fuel supply passage is subjected to a higher vacuum than when the engine is operating under normal idling conditions. This vacuum is gradually reduced as the vehicle slows down and ultimately the normal idling vacuum is reached. As long as the vacuum at the idling fuel inlet or inlets is greater than the normal idling vacuum, a larger quantity of fuel is introduced into the intake passage than will be burned, resulting in the discharge of unburned fuel into the atmosphere, through the exhaust conduit. This results in waste of fuel and contamination of the atmosphere.

Various devices have been provided for preventing the discharge of fuel from the idling fuel supply system into the intake passage during deceleration, as longasthe vacuum in the intake passage is greater than the normal idling vacuum, but which will be rendered inefiective after such deceleration as will bring about a reduction of vacuum in the intake passage to that which is maintained during the normal idle operation. With such devices as soon as. the vacuum drops to the normal idling vacuum,

the idling system again becomes effective to supply fuel.

Some difficulty has been encountered with devices of this kind because there is an appreciable delay involved in the resumption of engine operation, either idling or operation under load, after aperiod of deceleration for the reason that during deceleration, all of the fuelwhich is normally in the intake pipe and manifold has been drawn into the engine, so that when deceleration ends and normal operation is to be resumed, there is substantially no fuel in the entire intake system, the walls of the intake pipe and manifold, which are usually covered by a film offuel, being substantially dry. When the idling fuel system, or the main supply system in the event the throttle is opened immediately after deceleration, starts to function, it takes an appreciable period of time for fuel supplied by either system to reach the combustion chambers in sufficient quantity to effect satisfactory engine operation. This delay in effecting resumption of normal engine operation is alwaysobjectionable, causing the engine to run irregularly and even tending to cause the engine to stall. The elimination of this time lag in the resumption of normal engine operation. is, therefore, a matter of considerable importance.

It is, therefore, the primary purpose of the present in vention to provide a carburetor having mechanism which is effective to interrupt the flow of fuel from the carburetor into the intake system of the engine during a period of deceleration following closing of the throttle, when it the partial vacuum posterior thereto equals or exceeds a predetermined vacuum, but which will automatically cause The flow of fuel into the engine intake to be resumed when the vacuum posterior to the throttle falls below said predetermined vacuum, and which is provided with means whichwill supply to the intake passage substantially im mediately, when the vacuum falls below said predetermined vacuum, suflicient fuel to bring about resumption of normal engine operation Without appreciable delay. It is a further object to provide a carburetor equipped withdevices such as described in which such devices are simple in constnuction, positive in operation and are relatively:inexpens ive, so that the cost of the carburetor is increased but little.

In some instances devices of this kind have been provided in which the interruption to fuel flow has been effected by a cut-olf valve which blocks the fuel passage and is operable in response to variations in vacuum in the intake passage posterior to the throttle. According to the .present invention, interruption in fuel flow is effected; by a valve, operated by a suction operated memher when a predetermined suction or partial vacuum is reached posterior to the throttle, to open a vent admitting air to the idling fuel supply passage in such quantity as to. substantially prevent the flow of fuel therefrom. As long asthe predetermined suction referred to is equalled or exceeded, thevent valve remains open and no fuel is supplied through ,the idling system, but as the vehicle slows ;.down, the suction posterior to the throttle will be reduced and ul-tir'nately will drop below the predetermined suction. Whenthis takes place the. vent valve will be cl sedand flow of fuel from the idling system will be 7 resumed- The valve is actuated by a suction operated diaphragm j opening of the, vent valve, fuel is drawn into a chamber a secondary mixture passage 4.

of which the diaphragm constitutes'one wall. When the diaphragm moves in the opposite direction as the result of a dropin suction effective as the vehicle slows down,

the -movement'of the diaphragm forces fuel from the chamber into a passage through which air is flowing at very high velocity, so that such fuel is atomized and carried into the combustion chambers substantially simulta neou-sly.with the closing of the vent valve. resumption of normal operation is effected with substan- In this way tiall -y no delay when the suction effective on the diaphragrn falls below a predetermined suction.

\ Further objects and advantages of the present inventionwill be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

55. which is partly diagrammatic.

,Eig. 2 is an enlargeddetail section of the mechanism foroperating the fuel controlling valve.

, In FIig. 1 a part of a four-outlet carburetor is shown in vertical section, one entireprimary mixture passage,

designated 2 in its entirety, being shown and a part of 7 It will be understood that in a four-outlet carburetor there are two primary mixture passages 2 and two secondary passages 4, but if the carburetor is a dual outlet device, there is only one primary and one secondary mixture passage. While the subject, invention has been illustrated on a particular type carburetor, it is apparent that the invention is equally adaptable to other carburetor constructions.

, 'The carburetor shown in the drawings .is formed of three castings, positioned one above the other, and separated by suitable gaskets, these castings being a throttle .bodycasting- 6, a fuel chamber casting 8 immediately above the casting 6 and an air inlet casting 10 immediately above the fuel chamber casting. A fuel chamber 12, in which fuel is maintained at a substantially constant level, by means not shown, is formed in casting 8 and an air inlet opening 14 is formed in the casting 10.

A choke valve 16 secured to a rotatable shaft 18 controls admission of air to the mixture passage 2 and this valve may be controlled either manually or automatically, as desired, so far as the present invention is concerned. A throttle valve 20 secured to a rotatable shaft 22, which may be operated by any conventional means, not shown, controls the quantity of combustible mixture which is supplied to the engine in order to control the speed. A vent tube 24 extending into the mixture passage adjacent the air inlet maintains nearly atmospheric pressure in the fuel chamber in a well known manner.

Fuel is supplied by chamber 12 to a well 26 through a metering plug 30 which is screwed into a passage in casting 8 connecting the chamber 12 and the well. The plug has a constantly open fuel passage 32 and another passage 34 normally closed by a spring held check valve 36 which is opened at high speed operation. The fuel passing through both passages 32 and 34 flows through an opening in a fuel metering member 38 at the outlet end of metering plug 30. The well is vented as indicated at 39.

A small casting 40 is secured in any suitable way to the casting 8, as shown in Fig. 1, above the well 26 and a. fuel supply tube 42 having a closed lower end and a series of openings 44 therein extends down from the casting 40 into the well 26 and supplies fuel emulsion to a passage 46 formed in casting 40 and delivering such emulsion to a small venturi tube 48, that is also formed in casting 40, where the emulsion is mixed with additional air to form a primary mixture. This primary mixture is discharged into a large mixture tube 50 formed by the wall of casting 8, which constitutes the main mixing chamber and in which the primary mixture is mixed with additional air to form a fuel-air mixture of the desired combustible proportions.

An idling fuel well, not shown, supplies fuel for idling to the passage 52 formed in the wall of casting 8 and this passage connects with a channel 54 in the upper face of the casting 6, which leads to a vertical bore 56 also formed in casting 6. A bore 58 connects passage 56 with the mixture passage 2 at a point anterior to the throttle and a passage 60 connects the passage 56 with the mixture passage at a point posterior to the throttle. The bore 56 is primarily an air bleed while the passage 60 is a fuel supply passage which delivers fuel for idling to the mixture passage posterior to the throttle. The mechanism so far described is substantially similar to that fully shown and described in application Serial No. 264,136

of Olson et al., filed December 29, 1951 and reference may be had to that application for a complete description of the carburetor.

The effective area of the passage 60 is controlled by a manually adjustable valve 62 of conventional type which will be held in any adjusted position by a spring 64 positioned between the head of the valve and the carburetor housing, as is customary in substantially all commercial carburetors. With the throttle in the position shown, idling fuel is supplied only by the passage and air flows into the idling passage through the passage 58, but if the throttle is opened enough to bring the passage 58 to the posterior side of the throttle, such passage also serves to convey fuel from the passage 56 into the mixture passage in the manner well known.

As already indicated, means are provided which will automatically admit sufficient air to the idling fuel passage to prevent any flow of fuel therefrom when, during deceleration, the suction or vacuum in the mixture passage exceeds some predetermined vacuum. This means includes the passage 70 extending from the passage 56 to the outside of the carburetor housing anterior to the throttle and anterior to a restricting plug 72 which is positioned in the passage 56 between the passage and the throttle. The passage 70 connects with the atmosphere and is normally closed by a control valve 74 which is a flat disk having an opening at the center which surrounds a reduced end extension 76 of a valve actuating rod 78, between a shoulder 80 and a retaining washer 82, which is mounted on extension 76 between the end thereof and the valve. The valve 74 fits loosely enough on its support 76 to compensate for inaccuracies in alignment of the parts and to enable the valve to seat accurately on the housing surface surrounding the passage 70. This surface should, of course, be machined smooth so that the valve, when sealed, will effect complete closure of the passage 70.

The rod extends into a housing designated generally by the reference numeral 84 and comprises a cup-shaped member 86 to which the suction of the intake passage posterior to the throttle is communicated, a short cylindrical member 88, the space within which forms a fuel chamber and an end plate 90 which is secured to the cylinder 88 in any desirable way, as by bolts 92. Also the cylinder 88 is connected to member 86 by bolts 94, which extend through flanges on the cylinder and member respectively. At the end of the rod 78 which extends into the housing 84, it is connected to a flexible diaphragm of any suitable material which is resistant to the effect of hydrocarbon fuels and this diaphragm, at its peripheral edge, is clamped between the flanges 96 and 98 with sufficient pressure to prevent leakage. The rod 78, at its right end, also has a reduced extension 102 similar to the extension 76 which passes through an opening at the center of the diaphragm and also through two reinforcing metal washers 104 and 106, while the assembly of diaphragm and washers is held in position against a shoulder 108 on rod 78 in any suitable Way, as by riveting the end of extension 102 over the washer 106.

A spring 110 is positioned within the member 86 between the Washer 106 and a similar Washer or abutment member 112, secured to the end of a rod 114 which has threaded engagement with the wall of member 86, so that it may be adjusted by a suitable tool to vary the pressure exerted by the spring on washer 106. This spring pushes the diaphragm assembly, the rod 78 and the valve 74 toward the left to efiect closing of the valve when the suction which is communicated to the space within the member 86 is insufiicient to overcome the force of spring 110.

Positioned between the end plate 90 and the left end of the cylindrical member 88 is another diaphragm 116 and an annular washer 118 which has an opening 120 at the center thereof. The peripheral edges of this diaphragm and washer are clamped between the end plate and the element 88 with sufficient pressure to prevent leakage and the space within the cylinder 88, between the two diaphragms, constitutes a fuel chamber from which fuel is forced when the engine resumes normal operation after a period of deceleration, as more I fully described later.

Supported at the center of the diaphragm 116 is a sleeve-122 which surrounds the rod 78 and is slightly spaced therefrom, as clearly shown in Fig. 2. Positioned between the rod 78 and the sleeve are two 0 rings 124 of suitable sealing material which are received in suitable grooves formed on the inner surface of the sleeve. These rings prevent leakage of fuel around the rod 78, but permit movement of the rod relative to diaphragm 116. The rod has a loose enough fit with the end plate 90 to permit the rod to slide freely in the plate and an opening 126 admits air to the space 128 between the end plate 90 and diaphragm 116 so that the left side of the diaphragm is subject to atmospheric pressure.

. The suction or partial vacuum which is maintained within. the engine intake system posterior to the throttle 20 is communicated to the space within the member86 by means of a conduit 130 which connects at one end (not shown) with the intake "at any suitable point posterior to the throttle and atihe other end with a threaded boss 132 formed on the wall of the member 86 and communicates with a passage 134 which extends through the boss. The conduit, which may be of any suitable material such as a copper tube, is connected to the boss by any suitable means, such as a coupling nut 136.

During normal idling operation of the engine, the speed of the engine is rather low and the'suction in the intake passage which is communicated to the space within the member 86 is not sufficient to overcome the spring 110 and the valve 74 remains closed. Also under such .conditions the fuel which is supplied to the intake passage by the idling fuel supply system is substantially all burned by the engine so that unburned fuel is not discharged into the atmosphere through the exhaust. If, however, the throttle is closed, to effect deceleration of the vehicle, the engine will be driven by the vehicle and much faster than its normal idling speed. When this takes place, the suction which is maintained in the intake passage posterior to valve 20 and in the chamber 86 is considerably higher than the normal idling vacuum because the engine is operating at a speed considerably higher than the normal idling speed. Under such conditions, if no means was provided to control flow of fuel from the idling system the presence of this higher vacuum in the intake passage would result in alarger quantity of fuel being introduced into the intake passage than would be burned by the engine and the discharge of unburned fuel vapor into the atmosphere would be brought about.

In the device disclosed, the higher vacuum which is maintained in the chamber 86 is effective to move diaphragm 100 to the right against the pressure of the spring 110 and open the valve 74'to prevent discharge of fuel into the intake from the idling system and the degree of vacuum necessary to effect this action is determined by adjustment of the rod 114. As already indicated, the vacuum in the chamber 86 will fall during deceleration and as soon as the vacuumdrops below that necessary to overcome the pressure of spring 110,

'the latter will move the diaphragm 100 to the left and close valve 74.

As stated previously, the space within the cylinder 88 at the left of the diaphragm 100' is a fuel chamber and fuel is discharged from this chamber to be introduced into the intake passage substantially with the closing of valve 74. Fuel is supplied to the chamber within the cylinder 88 through the port 140 with the interior ofa cylindrical plug 142 screwed into the wall of the cylinder 88. A nipple 144 has threaded engagement With the plug and a passage 146 therethrough is normally closed by a spring held check valve 148. A fuel supply conduit is adapted to be connected to the nipple in any desirable way. A fuel delivery conduit .150 is formed in a threaded boss 152 which projects from the wall of the cylinder 88 and a fuel delivery conduit 154 is connected to such boss by any suitable coupling means. This conduit delivers fuel into a funnel 156 provided at the upper end of a fuel delivery conduit 158, the delivery end of which is connected in any suitable way with the intake passage at -a point posterior to the throttle 20. A spring held check valve .159 is pro- Vided in the passage 15% to prevent admission of air therethrough when the diaphragm 120 is moved to the right.

Obviously as the diaphragm 1% moves to the right to open the valve 74 a partial vacuum is created which would move the diaphragm 116 to the right also but since only a small part of the latter can move the partial vacuum created will enlarge the chamber between the diaphragms, will open valve 148. and draw fuel into such chamber. When the vacuum drops enough to permit movement of diaphragm 100 to the leftthe chamber is which communicates reduced to its normal size and fuel is forced out of such chamber throughthe conduit 154 and into the funnel 156. Since the conduit 158 connects with the intake passage posterior to the valve 20, it is subject to high vacuum, the normal idle vacuum, when the diaphragm moves to the left so that there is a very high velocity current of air going through the conduit 158 when fuel is delivered to the funnel 156. Therefore, the fuel delivered to the funnel is carried into the intake substantially simultaneously with the movement of the diaphragm to augment the fuel supplied by the idling sys tern, if the throttle remains-closed and the operation of the engine, when normal operation is resumed, is an idling operation. Also this high velocity air flow through conduit 158 aids in effective atomization and partial vaporization of fuel supplied thereto so that it moves at hi h velocity through the intake passage when supplied thereto.

If, after deceleration the'throttle is opened to bring about resumption of normal engine operation under drive conditions, the vacuum effective on the conduit 158 is reduced and the velocityof flow through such passage is reduced, but this is largely off-set by the fact that the vacuum within the member 86 is also rapidly reduced by the opening of the throttle. This will result in faster movement of the diaphragm 100 to the left and faster delivery of fuel into the funnel 156 so that the effect of the diaphragm in supplying extra fuel to the intake passage is about the same whether the engine, when it resumes normal operation, is operating at idle or under load with an open or partly open throttle.

In vehicles equipped with a manually operated transmission, if it be desired, after a period of deceleration to immediately resume operation of the vehicle under load, it is generally necessary to change gears and to do this it is necessary to disengage the clutch. According to the present invention, means are provided through the medium of which disengagement of the clutch will open a valve to admit air to the space within the member 86. This will increase the speed of movement of the diaphragm to the left and increase its effectiveness as a fuel pump, particularly as the clutch will be disengaged while the throttle is still closed and the delivery end of conduit 158 will be subject to high vacuum.

This means for introducing air into the space within member 86 upon disengagement of the clutch includes ,a passage 160 formed in a threaded boss 162 projecting from the member 86 to which a conduit 164i is connected by any suitable coupling means. The conduit communicates with a coupling member supported in any suitable manner on the vehicle. The conduit is connected to the member 168 by a coupling nut 170 and a valve housing 172, having a valve chamber therein, is screwed into the member 168 as indicated in Fig. 1. A port 174 connects the valve chamber with the atmosphere and this port is controlled by a spring held valve 176 which is normally closed, the spring being strong enough to hold the valve closed against the effect of the partial vacuum within the member 86.

Pivoted at 178, in the conventional manner on the clutch housing 180 is a clutch actuating lever 182, one end of which is pivotally connected to a valve actuating rod 184, the other end of which extends into the passage 174 so that when the lever 182 is moved counterclockwise to disengage the clutch, the rod 184 is moved to engage and open the valve 176 and, at the same time a link 186, which is connected to the lower end of lever 182, is moved to the right to disengage the clutch. Admission of air past valve 176 breaks the vacuum within the member 86 and permits rapid movement of diaphragm to the left, greatly increasing the rate of fuel delivery to the funnel 156.

The housing 84 is supported by a bracket 190 connected by a screw 192 to the carburetor housing and the housing may be connected to such bracket in'any suitable manner, while the funnel 156 may be supported by a bracket 194 also secured by a screw to the carburetor housing.

' A restricting plug 196 may be positioned in the passage 134 to control the rate of change in the vacuum Within the member 86 if desired. The size of the restriction in this plug will determine the rate of movement of the diaphragm in relation to the change in suction or vacuum in the intake passage posterior to the throttle 20.

It will also be understood that the closing of the valve 74 is effected not only by the spring 119, but also by the effect of suction communicated by the passage 70 to the left side of the valve 74 itself. However, it is apparent that the area of the valve which is subject to the aforesaid suction is very minor by comparison with the area of diaphragm 100 which is subject to the suction that is maintained within the member 86. Therefore, the principal force opposing the opening of the valve is the spring and the area of the valve which is subject to suction is in no sense critical.

It will also be understood that while in the device as disclosed, the element 116 is a flexible diaphragm of the same type as the diaphragm 100 such element could be a metal plate having little or no flexibility.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a fuel chamber adapted to be supplied by said fuel supplying means, a valve for controlling said passage, a suction operated member operatively connected to said valve and responsive to variations in engine suction posterior to the throttle, said suction operated member forming a part of said chamber, said member being movable to a position to open said valve and draw fuel into the fuel chamber when a predetermined suction is reached or exceeded posterior to said throttle, conduit means communicating said fuel chamber and said mixture passage, and means operative to move said member to a position to close said valve and to force fuel into said mixture passage when the suction posterior to said throttle falls below the predetermined suction.

2. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage, a housing including a movable wall therein, said housing and movable wall defining a fuel chamber into which fuel is drawn when said wall moves in one direction and from which fuel is discharged when said wall moves in the opposite direction, a fuel supply conduit therefor, a fuel discharge conduit adapted to supply fuel discharged from said chamber to the mixture passage, check valves in said fuel supply and discharge conduits insuring that fuel can only flow from the supply conduit to the discharge conduit, means operatively connecting said movable wall with said valve, said housing and movable wall also defining a vacuum chamber, means for communicating the suction of the mixture passage posterior to the throttleto said vacuum chamber, so as to effect movement of the wall in a direction to open said valve and draw fuel into said fuel chamber when the suctionposterior to the throttle equals or exceeds a predetermined suction, and means for moving said wall in the opposite direction to close said valve and discharge fuel from said fuel chamber when the suction posterior to the throttle falls below said predetermined suction.

3. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage, a housing, a fuel chamber in said housing and comprising two flexible walls of different area, one of said flexible walls and said housing defining a vacuum chamber, a passage communicating engine suction posterior to the throttle to said vacuum chamber, fuel supply and delivery conduits connecting said fuel chamber with a source of fuel supply and the mixture passage respectively, means for connecting said fuel controlling valve with the larger of said walls so as to be opened and closed thereby as the wall is moved in opposite directions, said walls being movable to open the valve and draw fuel into said fuel chamber when the suction posterior to the throttle equals or exceeds a predetermined suction and means for moving said walls in the opposite direction to discharge fuel from said fuel chamber and close the valve when the suction posterior to. the throttle falls below said predetermined suction.

4. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage, a housing, a flexible partition in said housing dividing said housing into two chambers, one of which is a fuel chamber and the other a vacuum chamber, fuel supply and delivery conduits connecting the fuel chamber with a source of fuel supply and the mixture passage, an operating member extending into said housing and connecting the fuel controlling valve with said partition, means for communicating the engine suction posterior to the throttle to said vacuum chamber to move said partition to open said valve and draw fuel into the fuel chamber when the suction in the vacuum chamber equals or exceeds a predetermined suction and means in said vacuum chamber for moving said partition in the opposite direction to discharge fuel from the fuel chamber and close said valve when the suction in said vacuum chamber falls below said predetermined suction.

5. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to'the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said'conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuelconduit, a valve for controlling said passage, a housing, a flexible partition in said housing dividing said housing into two chambers, one of which is a fuel chamber and the other a vacuum chamber, fuel supply and delivery conduits connecting the fuel chamber with a source of fuel supply and the mixture passage, an operating member extending into said housing and connecting the fuel controlling valve with said partition, means for communicating the engine suction posterior to the throttle to said vacuum chamber to move said partition to open said valve and draw fuel into the fuel chamber when the suction in the vacuum chamber equals or exceeds a predetermined suction and a spring positioned in said vacuum chamber for moving said partition in the opposite direction to discharge fuel from the fuel chamber and close said valve when the suction in said vacuum chamber falls below said predetermined suction.

6, In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage, a housing, a flexible partition in said housing dividing said housing into two chambers, one of which is a fuel chamber and the other a vacuum chamber, fuel supply and delivery conduits connecting the fuel chamber with a source of fuel supply and the mixture passage, an operating member extending into said housing and connecting the fuel controlling valve with said partition, means for communicating the engine suction posterior to the throttle to said vacuum chamber to move said partition to open said valve and draw fuel into the fuel chamber when the suction in the vacuum chamber equals or exceeds a predetermined suction, a spring positioned in said vacuum chamber between said partition and an abutment member and operative to move the partition in the opopsite direction to discharge fuel from the fuel chamber and close said valve when the suction in said vacuum chamber falls below said predetermined suction and means for adjusting the position of the abutment member to vary the pressure exerted by said spring on the partition and the suction required to open the fuel controlling valve.

7. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage and a suction operated member operatively connected to said valve, said member being movable to open said valve when the suction effective thereon equals or exceeds a predetermined suction and movable to close said valve when the suction effective on said member falls below said predetermined suction, means for communicating the suction posterior to the throttle to said member and manual means for modifying the suction effective on said member independently of the suction maintained posterior to said throttle.

8. In a carburetor for use on an automotive vehicle having an internal combustion engine and a drive shaft connectible to the engine through the medium of a clutch operable by a manually operable clutch lever, said carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of 7 mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage and a suction operated member operatively connected to said valve, said member being movable to open said valve when the suction elfective thereon equals or exceeds a predetermined suction and movable to close said valve when the suction effective on said member falls below said predetermined suction, means for communicating the suction posterior to the throttle to said member and means operable by said clutch lever to modify the suction effective on said member when the clutch lever is actuated to operate the clutch.

9. In a carburetor for use on an automotive vehicle having an internal combustion engine and a drive shaft connectible to the engine through the medium of a clutch operable by a manually operable clutch lever, said carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage and a suction operated member operatively connected to said valve, said member being movable to open said valve when the suction effective thereon equals or exceeds a predetermined suction and movable to close said valve when the suction effective on said member falls below said predetermined suction, means for communicating the suction posterior to the throttle to said member and means operable by said clutch lever to reduce the suction effective on said member whenever the clutch lever is actuated to disengage the clutch.

10. In a carburetor having a mixture passage adapted to supply a combustible mixture of fuel and air to an internal combustion engine, a throttle for controlling the quantity of mixture supplied thereto, means for supplying fuel and air to the mixture passage including an idling fuel conduit for supplying fuel to the mixture passage posterior to the throttle, means for preventing the flow of fuel from said conduit during deceleration following a closing movement of the throttle, said last named means comprising an air passage for introducing air into said fuel conduit, a valve for controlling said passage, a housing, a suction operated member disposed in said housing for moving said valve responsive to variations in engine suction posterior to the throttle, said member being movable to open said valve when the engine suction equals or exceeds a predetermined suction and movable to close said valve when the suction falls below said predetermined suction, said housing and said suction operated member defining a fuel chamber from which fuel is discharged by movement of said suction operated member when moved to close said valve, a conduit communicating with the atmosphere at one end and the mixture passage posterior to the throttle at the other end so as to maintain a very high velocity air flow through said conduit and means for delivering fuel discharged from said chamber into said last named conduit.

References Cited in the file of this patent UNITED STATES PATENTS 2,212,936 Hoof Aug. 27, 1940 

